Help to get started

I am new to Java, really new, but need to use the datagrid for a web application (I am using php for database access and other things.)

I would be very happy if someone could give me examples how to go from selecting a row in the datawidget (I manage to get the widget, fill it with my data, and it is looking nice (scrollable,....)). But I have no idea how to go from there. If I double click on a row I want to get (some) of the data into a variable (in a php-script) and use whatever infor in the row to put in a sql-statement for retrieving other data from the database......